Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 231941 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 341 PM EDT Fri Sep 23 2016 .SYNOPSIS...
-- Changed Discussion --
A cold front will cross the region this evening, bringing lower temperatures. A band of rain showers is also expected behind this front later this evening into tonight, but amounts will be light. Cool and dry weather will follow this weekend into early next week. A slow-moving low pressure and cold front could lead to some showers late next week.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Latest mesoanalysis continues to show a very unfavorable environment for supporting thunderstorms across southern New England. Abundant clouds, as well as a stout low level inversion, from earlier today has limited our warm up. More sunshine developing across southern New England this afternoon. But it may be a case of too little, too late. Looking upstream, lots of lower clouds behind a cold front across southern VT and NH. That indicates more abundant moisture, and the possibility of some showers. Short-term guidance, such as the HRRR and RAP, continues to indicate a higher likelihood of at least some lightly measuring showers. Will continue with a brief period of chance PoPs this evening. Only moderate confidence rainfall chances will actually be as high as suggested by the guidance with few radar returns upstream, despite the run-to-run consistency of the guidance. Band of rain showers will continue to press from north to south with band of mid level frontogenesis/moisture behind a cold front. Much cooler air will continue to work into the region tonight and northeast winds will be a bit gusty along the coast.
-- End Changed Discussion --
&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
Drier air will move in from the northwest, allowing for skies to become mostly sunny during the morning. Mostly clear skies continue through Saturday night. Below normal temperatures during this time as well. If winds can diminish enough, there is the remote possibility of some frost across portions of the east slopes of the Berkshires Saturday night, particularly in Franklin county. Will need to monitor this, but think it is a low probability event at this time. However, a fall-like atmosphere will be in place with 850T between +3C and +5C. High temps should still recover well into the 60s to near 70 given lots of sunshine, but certainly be our first true taste of early fall.
-- End Changed Discussion --
&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
Highlights... * Cool and dry weather follows for this weekend into next week. * Patchy frost possible for some interior locations Sunday night. * Seasonable temperatures late next week Overview and model preferences... Highly amplified flow regime continues development mainly as sharp rex block continues to move across E Canada and the US. This provides a conduit for cooler air from near Hudson`s Bay into New England, delivering a period of below normal temperatures, and very comfortable dwpts. Ensembles and deterministic guidance are in good agreement through Tue in spite of the meridional pattern. Beyond Tue, there begins to be more significant difference regarding how quickly cutoff low pres moving E of the continental divide is able to open and become more progressive. ECENS mean continues to be a good middle ground in timing/impacts. Splitting the very slow GFS and more progressive ECMWF. Therefore, from Wed onward, will continue to add more weight to the ECENS mean, which agrees with WPC thinking. Details... Sun through Mon... Cooler and fall-like conditions prevail as H85 temps drop as low as 0C to +2C late Sun before warming back up to about +6C Mon. Expect highs mainly in the low-mid 60s to prevail. Very low dwpts expected thanks to good afternoon mixing, as low as the mid 30s in spots. Therefore, should radiational cooling be observed, there is a low risk for frost each early morning Sun and Mon, particularly in the most sheltered NW MA valleys. Not expecting widespread frost as developing inversions look to reach only the upper 30s at their coolest with 40s elsewhere each night. Tue and Wed... Uncertainty begins, but will need to monitor for stacked low pres to approach from the W-NW with a warm frontal, then cold frontal passage. Timing very uncertain, but using the ECENS mean, will focus POPs mainly late Tue into early Wed. PWATS mean is only about 1.0 to 1.5 inches with highest probs closer to 1.0 inches, so while rain showers are possible it will be dependent on timing and still may not amount to much more than a quarter inch. Temperatures rise, but may hold close to seasonal normals. Mainly upper 60s and low 70s for highs while mins drop into the 50s. Thu and Fri... As previous forecaster noted, given the slow movement and involvement of a cutoff low pres featuring heights 2 std deviations below normal, not confident on how quickly the impacts from this feature leave New England. Low pres could redevelop in the Gulf of Maine or Maritimes as what is left of the cutoff shifts to the E leading to a resurgence of moisture back into New England should the new cyclogenesis be close enough. At this time, will continue with NIL or low POPs due to uncertainty until the Meridional pattern is better progged.
-- End Changed Discussion --
&& .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...Moderate to high confidence. A period of MVFR CIGS in a band of showers are likely behind a cold front. Northeast wind gusts of 20 to 25 knots expected along the coast. Saturday...High confidence. Mainly VFR. Any leftover MVFR Cigs, and perhaps some patchy early morning fog in the typical locations, will improve to VFR by mid morning. Saturday night...High confidence. VFR. KBOS TAF...Moderate confidence in TAF due to shower coverage. High confidence in winds. Wind shift to the northeast with brief gusts to 25 kt possible between 23/20Z and 24/06Z, along with a period of MVFR CIGS and showers. KBDL TAF...Moderate confidence in TAF due to shower coverage. High confidence in winds. Outlook /Sunday through Tuesday/... Sunday into Mon...High confidence. VFR. Some 25 kt wind gusts possible near shore Sun out of the NW. Tue...Moderate confidence. Timing uncertain, but some showers possible on Tue with localized MVFR or lower conditions.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence. A strong cold front should result in a period of northeast wind gusts up to 25 knots, and 3 to 6 foot seas across our open waters, early this evening into the overnight hours. Small craft headlines posted for all waters except Narragansett Bay. Saturday into Saturday night...High confidence. Leftover 25 kt wind gusts diminish by mid morning as pressure gradient weakens. However, small craft headlines will continue across our outer waters into mid afternoon from leftover swell. These seas should finally drop below small craft advisory thresholds by late afternoon. Increasing north to northwest winds with a stronger surge of colder air over the waters. Not confident there will be a long period of sub advisory winds. So, will continue the small craft advisory into Saturday night across the outer coastal waters. Outlook /Sunday through Tuesday/... Sunday into Sun night...High confidence. Small craft advisory conditions prevail. NW winds gust around Sat night into daytime Sun with seas building 5-6 ft on the ocean waters. Although winds recede by Sun night, it will take the remainder of the night for seas to fully drop below the 5 ft threshold. Mon and Tue...Moderate confidence. Mainly quiet boating weather but an approaching front could yield more small craft advisory conditions Tue. However, this is timing dependent, which is uncertain.
-- End Changed Discussion --
&& .BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 PM this evening to 8 AM EDT Saturday for ANZ231>235-237. Small Craft Advisory until 11 PM EDT this evening for ANZ230. Small Craft Advisory until 6 AM EDT Sunday for ANZ250. Small Craft Advisory until 8 AM EDT Saturday for ANZ251. Small Craft Advisory from 8 PM this evening to 6 AM EDT Sunday for ANZ254>256.
-- End Changed Discussion --
&& $$ SYNOPSIS...Belk/Doody NEAR TERM...Belk SHORT TERM...Belk LONG TERM...Doody AVIATION...Belk/Doody MARINE...Belk/Doody

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.